I think you could do a lot worse than going for a 1.3 transplant. Ported and skimmed head, higher lift cams, 4-2-1 manifold, Sportex or Ashley system (with decat pipe), heatwrapped manifold, Almera airbox with K&N panel filter, 1.6 injectors, iridium spark plugs, remove aircon (if you have it), and strip the interior out - I think you can get the weight down to about 600kg if you remove everything apart from the front seats, steering wheel, and dashboard. My mate has done less than this to his SR, and it flies :grinning:
I also seem to remember that there was a thread on here where someone managed to gain something like 30bhp/40bhp, purely by customising a higher capacity throttle body, making their own high lift cams, and a few other mods - all you would require for that is some skill and patience. I'm sure someone will remember which thread I'm on about :laugh: